Neurotensin (NT), released from the intestine by ingestion of fat, slows gastric emptying, stimulates pancreatic secretion, and enhances the uptake of fatty acids. The primary goal of the present application is to study the mechanisms by which NT promotes bile acid output and to understand the nature of the feedback loops which control NT synthesis and secretion. Studies will involve determining the mechanisms of action of NT; that is, whether its effects on increasing bile acid output are secondary to an increase in hepatic synthesis of bile acid and/or involve increased intestinal uptake. In addition, studies to investigate the feedback effects of bile acid on NT receptor expression are planned. Additional studies will determine the effects of the NT antagonist SR48692 on enterohepatic fat function and fat absorption.